Metal rectifier of the selenium type



Jgn. 3, 1950 E. A. RICHARDS METAL RECTIFIER OF THE SELENIUM TYPE Filed Dec. 15. `1944 Planted Jin. 3, 195o oFFlCl-z METAL :morn-mn oF uns: SELENIUM ma Edward Arthur Richards, London, England, as-

signor, by mesne assignments. to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application December 15, 1944, Serial No. 568,237 In Great Britain January 15, 1944 z claims. (ci. ris-ssc) This invention relates to metal rectiiiers of the selenium type and is a modification of the so-called center contact rectiiler as disclosed in U. S. Patent No. 2,314,104.v

According to the present invention the active electrode of each element is in part insulated from the metal base in such a manner that when pressure is applied to the element the pressure on the counterelectrode and the active electrode oi' an element is limited to that portion which is insulated from the metal base. y

Referring now to the accompanying drawing which shows diagrammatically and by way of example embodiments of the invention:

Fig. l is a central sectional elevation of one rectiner element according to the invention mounted on an insulating spindle; and

F182 2 is a central sectional elevation of a different form of rectifier element according to thel invention adapted to be mounted, for example,

in a tube as shown in Fig. 3 of the aforesaid patent. Y

In these drawings the reference I indicates the metal base or disc of iron or other suitable metal and 2 is the selenium coating. A washer or coating of insulating material I is applied to the base plate tc cover a portion thereof as shown, before the selenium coating is applied and the counterelectrode ,4 is applied to the selenium' coating as by spraying in the usual manner. The position of a second element in each figure is indicated in dotted lines.

As shown in Fig. l, a metal contact washer i may be to be pressed tightly against the counterelectrode I as inthe previously mentioned patent, the-element being mounted on an insulated spindle l ,by which several such elements may be clamped together in known manner. It will thus be seen that the active portion of the element is relieved from pressure.

The present invention may be applied to many diii'erent aises and shapes of rectiiiers and the embodiment shown in Fig. 2 is ofvspeci'al importance in connection with very small rectiiiers in' which the elements may be assembled in an insulating' tube as described in the aforesaid'pat ent. The ring of insulating material 3 is applied to thebase plate and determines the active surface of the rectiiler element. Thus the effective rectifier portion is in the center which is relieved from pressure when the elements are assembled as the pressure is coniined to the portion covered by the insulating material.

What is claimed is: 1

1. A metal rectiiier comprising a metal base,

an insulating layer covering a portion of said base, a semi-conductor layer on said base and a counter-electrode layer on said semi-conductor layer, both said semi-conductor layer and said counter-electrode layer overlying said insulating layer. y

` 2. In a rectifier stack having means to apply pressure and hold a plurality of metal rectiiiers in stacked relation; a metal rectiiier comprising a metal base, an insulating layer covering an area lof said base over which said stacking pressure is applied,` a semi-conductor layer on said base and a counter-electrode layer on said semiconductor layer.- both said semi-conductor layer and said counter-electrode layer overlying said insulating layer, the presence of said insulating layer operating to preserve substantially the reverse current characteristic established between the semi-conductor and counter-electrode layers when pressure is applied thereover in the area of said insulating layer.-

REFERENCES errno l The following references are" of record in the me ci this patent:

` Umrnn sTA'rss Pa'rsNrs Number Name Date f 2,314,104 Richards et si. nur. 1c.v 194s 2,345,122 Herrmann ---4---- Mal'. 28, 19- 

